Kaijinbou is a former apprentice of Toutousai and the creator of the sword Toukijin. He appears in Episode 43-45. He was cast from under Toutousai's wing after being caught making evil swords. It was said that he killed several children (10, I believe was said in the anime) and poured their blood over the sword so that evil would dwell upon it. He is asked to forge a sword from the teeth of one of Naraku's children named Goshinki by Sesshoumaru after Toutousai refused. Looking for a chance to get back at his former Sensei, he accepted. After forging the blade, Toukijin, the sword took control of his mind using Kaijinbou to exact it's revenge on it's killer, Inuyasha.
Submitted by Khaoticfolks